1. Field of the Invention
The present invention relates to a device, such as an electron microscope, a laser microscope, a scanning probe microscope or the like, for observing minute structures, and particularly to a method of automatically setting a coordinate conversion factor in such an observing device.
2. Description of the Related Art
When observing a specified minute structure on a sample through a shape observing device, it is required that a coordinate value of the minute shape in a sample coordinate system be converted into a coordinate value in a stage coordinate system. Hitherto, as a method of obtaining the factor of conversion between the distinct coordinate systems, the following two methods have been used.
In a first method, a conversion factor at a predetermined position has been calculated in advance, and while detecting a position of the contour of each sample by a sensor or the like, the sample is mounted at the predetermined position, thereby to utilize the above-mentioned conversion factor.
In a second method, an operator searches for an objective such as a distinctive point of the contour of a sample, a positioning mark or the like, a coordinate position of which has been previously known, and then calculates a required number of coordinate values in both of the sample coordinate system and the stage coordinate system, from the result of which the conversion factor is calculated.
However, in the above first method, a machine control mechanism for detection of an optimum position is required, resulting in a complicated device structure.
In the above second method, the operation performed by the operator is troublesome and the accuracy in the conversion factor is degraded by an error of an objective position input depending upon the degree of proficiency of the operator.